A V6 ENGINE is a
V engine with six cylinders mounted on the
crankshaft in two banks of three cylinders, usually set at either a 60
or 90 degree angle to each other. The V6 is one of the most compact
engine configurations, usually ranging from 2.0 L to 4.3 L
displacement (however, much larger examples have been produced for use
in trucks), shorter than the inline 4 and more compact than the V8
engine . Because of its short length, the V6 fits well in the widely
used transverse engine front-wheel drive layout.

The V6 is commercially successful in mid-size cars in the modern age
of high fuel prices and price sensitive consumers because it is less
expensive to build and has better fuel consumption than the V8, while
being smoother in large sizes than the inline 4, which develops
increasingly serious vibration problems in larger engines. The wider
90° V6 will fit in an engine compartment designed for a V8, providing
a low-cost alternative to the V8 in an expensive car, while the
narrower 60° V6 will fit in most engine compartments designed for an
I4, proving a more powerful and smoother alternative engine to the
four. While not perfectly smooth, the V6 is smoother than the I4 and
adequately smooth for the average consumer. Buyers of luxury and/or
performance cars who are not price sensitive or fuel economy minded
might prefer an inline 6 , which has comparable fuel economy and power
but better smoothness, a flat 6 which combines better smoothness and
often higher power with adequate fuel economy, or a V8 which has
higher power, but worse fuel economy.

Recent forced induction V6 engines have delivered horsepower and
torque output comparable to contemporary larger displacement,
naturally aspirated V8 engines, while reducing fuel consumption and
emissions, such as the
Volkswagen Group 's 3.0 TFSI which is
supercharged and directly injected , and
Ford Motor Company 's
turbocharged and directly injected EcoBoost V6 , both of which have
been compared to Volkswagen's 4.2
V8 engine .

Modern V6 engines commonly range in displacement from 2.0 to 4.3 L
(120 to 260 cu in), though larger and smaller examples have been
produced, such as the 1991 Mazda MX3 , and the
Rover KV6 engine .

In Europe, where petrol is much more expensive than in the USA, V6
diesels have proved a more popular option. The American-designed
Chrysler 300C has a 3-litre Mercedes V6 engine, which vastly outsells
the petrol-engined car.

HISTORY

Some of the first V6-powered automobiles were built in 1905 by Marmon
. This firm became something of a V-engine specialist; beginning with
V2 engines, then V4s, V6s, V8s, and, in the 1930s, a
V16 engine .
Marmon was one of the few automakers of the world to offer a V16
-powered automobile.

From 1908 to 1913 the
Deutz Gasmotoren Fabrik produced
gasoline-electric train sets (Hybrid) which used a V6 as generator
engine.

In 1918 Leo Goosen designed a V6-powered car for
Buick Chief Engineer
Walter L. Marr . Only one prototype
Buick V6 car was built in 1918; it
was long used by the Marr family.
Lancia V6

The first series-production V6 was introduced by
Lancia in 1950 with
the
Lancia Aurelia model.
Lancia sought a smoother and more powerful
engine that would fit into an existing narrow engine bay. A Lancia
engineer, Francesco De Virgilio, began analyzing the vibration of
alternative V-angles for a
V6 engine in 1943. He found that a V6 with
its cylinders positioned at a 60° V-angle could be made uniquely
smooth-running in comparison with other possible V-angles. There was
resistance to his conclusion, because the V6 was a virtually unknown
engine type in the 1950s. His design featured four main bearings and
six crankpins, resulting in evenly spaced firing intervals and low
vibrations.

Other manufacturers took note and soon other V6 engines were
designed. In 1959, General Motors' GMC Truck division introduced a new
60-degree heavy-duty 305 in3 (5.0 L ) gasoline-fueled 60° V6 for use
in their pickup trucks and Suburbans ; this engine design was later
enlarged to 478 in3 (7.8 L) for heavy truck and bus use. The use of
the sweet spot of 60 degrees' V-angle maximized power while minimizing
vibration and exterior dimensions of the engine. In short, GMC
introduced a compact V6 design at a time when the straight-six engine
was considered the pinnacle of 6-cylinder design.

1962 saw the introduction of the
BuickSpecial , which offered a new
90° V6 with uneven firing intervals that was derived from—and
shared some parts commonality with—a small
BuickV8 engine of the
period. To save design time and expense, it was built much like a V8
that had two cylinders chopped off. The combination of a 90° V-angle
with only three crank pins—set at 120° apart, with opposing
cylinders sharing a crank pin as most V8 engines do—the cylinders
fired alternatively at 90 and 150° of crankshaft rotation. This
uneven firing caused harmonic vibrations in the drive train that were
perceived as a rough-running engine by the buyers. GM sold the engine
tooling to
Kaiser-Jeep in 1967; later, as a result of the 1973 oil
crisis , GM repurchased the tooling in 1974. In 1977,
Buick introduced
a split pin crankshaft to implement an even-fire version of this
engine in which cylinders fired consistently every 120°.

BALANCE AND SMOOTHNESS

The V6 does not have the inherent freedom from vibration that the
inline-six and flat-six have, but it can be modeled as two separate
straight-3 engines sharing a crankshaft. Counterweights on the
crankshaft and a counter rotating balance shaft are required to
compensate for the first order rocking motions.

Straight engines with an odd number of cylinders are inherently
unbalanced because there are always an odd number of pistons moving in
one direction while a different number move the opposite direction.
This causes an end-to-end rocking motion at crankshaft speed in a
straight-three engine . V6 designs will behave like two unbalanced
three-cylinder engines running on the same crankshaft unless steps are
taken to mitigate it, for instance by using offset journals or flying
arms on the crankshaft or a counter-rotating balance shaft .

In the straight-six engine layout, the two halves of the engine are
mirror images of each other and the end-to-end rocking motions of each
half become a bending moment which can be resisted by using a
sufficiently stiff engine block. In the horizontally opposed flat-6
(an example being the "boxer"-type engine), layout the rocking motions
of the two straight-three cylinder banks almost completely offset each
other, except for a small moment caused by the fact that the cylinders
must be offset slightly. This results in an engine which is short,
light, and relatively smooth, but too wide for most engine
compartments. It is widely used in light aircraft though, and in some
automobile engines, by manufacturers such as
Porsche and
Subaru .

In the V6 with 120° between banks, pairs of connecting rods can
share a single crank pin, but the two cylinder banks run like two
inline 3 , both having an end-to-end rocking couple. Unlike in a V8
engine with a crossplane crankshaft, the vibrations from one bank do
not cancel the vibrations from the other, so a rotating balancing
shaft is required to compensate for the primary vibrations. Because
the 120° V6 is nearly as wide as a 180° flat-6 but is not nearly as
smooth, and can be more expensive if a balancing shaft is added, this
configuration is seldom seen in production engines.

In the V6 with 90° between cylinders, split crank pins are required
to offset the connecting rods by 30° to achieve an even 120° between
firing intervals, and crankshaft counterweights are required to offset
the primary imbalances. In the 90° V6, a balancing shaft is desirable
but not entirely necessary to minimize second-order vibrations,
depending on the level of smoothness required. The main advantage of
the 90° V6 is that it can easily be derived from an existing 90° V8
design, and use the same parts as the V8.

Unfortunately, a 90° V6 cannot use the same technique that balances
an even firing 90° crossplane
V8 engine ; rotating the middle two
cranks to 90° from the outer two, using extra-heavy counterweights on
the crankshaft to offset the rocking motion, and then using the mass
of the pistons in the other cylinder bank at 90° to counteract the
side-to-side rotation that the heavy counterweights would otherwise
cause (resulting in an engine that is in perfect primary and secondary
balance, albeit one with very heavy crankshaft counterweights and
uneven firing intervals into the exhaust headers, resulting in the
familiar V8 "burbling" exhaust note).

A simple 90° V6 cannot achieve the same smoothness with only
crankshaft counterweights, and if the 90° V6 uses shared crankpins
like the V8, the engine will have uneven firing intervals, such as in
the original "odd-fire"
BuickV6 engine . This uneven firing interval
results in roughness at idle and low RPM, and varying harmonics at
higher engine speeds, making the "odd-fire" configuration unpopular
with buyers, so most manufacturers now use split crankpins to make the
firing intervals an even 120°. Therefore, designing a smooth V6
engine is a much more complicated problem than the straight-6, flat-6,
and V8 layouts. Although the use of offset crankpins, counterweights,
and flying arms has reduced the problem to a minor second-order
vibration in modern designs, all V6s can benefit from the addition of
auxiliary balance shafts to make them completely smooth.

When
Lancia pioneered the 60° V6 in 1950, they used a 60° angle
between the cylinder banks and a six-throw crankshaft to achieve
equally spaced firing intervals of 120°. This still has some balance
and secondary vibration problems. When
Buick designed a 90° V6 based
on their 90° V8, they initially used a simpler three-throw crankshaft
laid out in the same manner as the V8 with pairs of connecting rods
sharing the same crankpin, which resulted in firing intervals
alternating between 90° and 150°. This produced a rough-running
design which was unacceptable to many customers. Arguably, the
roughness is in the exhaust note, rather than noticeable vibration, so
the perceived smoothness is rather good at higher RPM. Later, Buick
and other manufacturers refined the design by using a _split-pin_
crankshaft which achieved a regular 120° firing interval by
staggering adjacent crankpins by 15° in opposite directions to
eliminate the uneven firing and make the engine reasonably smooth.
Some manufacturers such as
Buick in later versions of their V6 and
Mercedes Benz have taken the 90° design a step further by adding a
balancing shaft to offset the primary vibrations and produce an almost
fully balanced engine.

Some designers have reverted to a 60° angle between cylinder banks,
which produces a more compact engine, but have used three-throw
crankshafts with flying arms between the crankpins of each throw to
achieve even 120° angles between firing intervals. This has the
additional advantage that the flying arms can be weighted for
balancing purposes. This still leaves an unbalanced primary couple,
which is offset by counterweights on the crankshaft and flywheel to
leave a small secondary couple, which can be absorbed by carefully
designed engine mounts.

Six-cylinder designs are also more suitable for larger displacement
engines than four-cylinder ones because power strokes of pistons
overlap. In a four-cylinder engine, only one piston is on a power
stroke at any given time. Each piston comes to a complete stop and
reverses direction before the next one starts its power stroke, which
results in a gap between power strokes and annoying harshness,
especially at lower revolutions. In a six-cylinder engine (other than
odd-firing V6s), the next piston starts its power stroke 60° before
the previous one finishes, which results in smoother delivery of power
to the flywheel. In addition, because inertial forces are proportional
to piston displacement, high-speed six-cylinder engines will suffer
less stress and vibration per piston than an equal displacement engine
with fewer cylinders.

Comparing engines on the dynamometer , a typical even-fire V6 shows
instantaneous torque peaks of 150% above mean torque and valleys of
125% below mean torque, with a small amount of negative torque (engine
torque reversals) between power strokes. On the other hand, a typical
four-cylinder engine shows peaks of nearly 300% above mean torque and
valleys of 200% below mean torque, with 100% negative torque being
delivered between strokes.

In contrast, a
V8 engine shows peaks of less than 100% above and
valleys of less than 100% below mean torque, and torque never goes
negative. The even-fire V6 thus ranks between the four and the V8, but
closer to the V8, in smoothness of power delivery. An odd-fire V6, on
the other hand, shows highly irregular torque variations of 200% above
and 175% below mean torque, which is significantly worse than an
even-fire V6, and in addition the power delivery shows large harmonic
vibrations that have been known to destroy the dynamometer.

A
V6 engine with a 60 degree included angle between cylinder banks
hits the "sweet spot" in
V6 engine design due to several desirable
characteristics. Unlike most other V6 layouts, 60 degree engines can
be made acceptably smooth without using a balance shaft . Although the
engine will not be as smooth-running as an inline six or opposed six
cylinder engine, modern design and mounting techniques can eliminate
objectionable vibration.

In the 60 degree design, the connecting rods are attached to
individual crankpins, which are angularly displaced at 120 degree
intervals. This geometry results in an even firing interval,
eliminating primary vibration and reducing secondary vibration to
acceptable levels.

Lancia 's pioneering design in 1950 utlized a six-throw crankshaft to
achieve the required 120 degree angular displacement between
crankpins. The GMC V6 engine, designed for commercial vehicles, also
used a six-throw crankshaft, and was intentionally made physically
massive in order to further dampen vibration, as well as to enhance
durability. However, more recent designs often use a three-throw
crankshaft with what are termed _flying arms_ between the crankpins,
which not only produce the required angular crankpin displacement, but
also can be used for balancing purposes. Combined with a pair of heavy
counterweights on the crankshaft ends, flying arms can eliminate all
but a modest secondary imbalance, which can readily be dampened by the
engine mounts.

The 60 degree design is one of the most compact engine layouts, being
nearly a perfect cube that will fit longitudinally or transversely in
most engine compartments. Hence the 60 degree configuration is a good
fit in automobiles which are too large to be powered by four-cylinder
engines, but in which compactness and low cost are important
considerations. The most common 60 degree V6s were produced by General
Motors (the aforementioned GMC commercial engine, as well as a design
used in many GM front-wheel-drive automobiles) and
Ford European
subsidiaries (Essex V6 , Cologne V6 and the more recent Duratec V6 ).
Other 60 degree V6 engines are the
Chrysler 3.3 engine , the
Nissan VQ
engine , the
Mazda K engine , the
Alfa Romeo V6 engine , the
Mitsubishi 6G7 series of engines, many Toyota V6 engines and later
versions of the
Mercedes-Benz V6 engine.

90 DEGREES

Many manufacturers, particularly American ones, built V6 engines with
an angle of 90 degrees because they already had a successful V8 and
needed to create a smaller, lighter engine with better fuel economy to
meet market demand. Such configurations were easy to design by
removing two cylinders from an existing
V8 engine design. In some
cases, the first prototypes were created by simply sawing two
cylinders out of a V8 engine, welding the block back together, and
forging a 3-throw crankshaft to replace the V8 4-throw crank. This
reduced design costs, allowed the new V6 to share components with the
old V8, and sometimes allowed manufacturers to build V6s on the same
production line as V8s. MG Rover groups K
V6 engine

Although it was relatively easy to create a 90° V6 by simply cutting
two cylinders off an existing V8 engine, this produced an engine which
was wider and more vibration-prone than a 60° V6. The design was
first used by
Buick when it introduced its 198 CID _Fireball V6_ as
the standard engine in the 1962
Special . The
Buick V6 was notable
because it had uneven firing intervals between power strokes as a
result of using the 90° cylinder bank angle and sharing crankpins
between piston pairs as in the V8 engine. Rather than firing evenly
every 120° of crankshaft rotation, the cylinders fired alternately at
90° and 150°, resulting in strong harmonic vibrations at certain
engine speeds. These engines were often referred to by mechanics as
"shakers", due to the tendency of the engine to vibrate at idle speed.
Other examples included the
Maserati V6 used in the
Citroën SM , the
PRV V6, the Rover KV6 (2.0- and 2.5-litre), the
Honda C engine used in
the NSX ,
Chevrolet 's 4.3 L _Vortec 4300_ and Chrysler 's 3.9 L (238
in3) _Magnum V6_ and 3.7 L (226 in3) _PowerTech V6_ .

More modern 90°
V6 engine designs avoid these vibration problems by
using more sophisticated crankshafts with split crankpins offset by
30° between piston pairs to make the firing intervals an even 120°.
They often add balancing shafts to eliminate the other vibration
problems inherent in the layout. Examples include the later versions
of the
Buick V6,
Chevrolet Vortec 4300 , and earlier versions of the
Mercedes-Benz V6. The 90° Mercedes V6, although it was designed to be
built on the same assembly lines as the V8, used split crankpins, a
counter-rotating balancing shaft, and careful acoustic design to make
it almost as smooth as the inline-6 it replaced. However, in later
versions Mercedes changed the cylinder banks to a 60° angle to make
the engine more compact and eliminate the balancing shaft. Despite the
difference in V angles, Mercedes modified its production lines so it
could build 60° V6s on the same assembly lines as 90° V8s.

120 DEGREES

At first glance, 120° might be considered the _natural_ angle for a
V6 since pairs of pistons in alternate banks can share crank pins in a
three-throw crankshaft, and the cylinders will fire evenly every 120°
of crankshaft rotation. Unlike the 60° or 90° configurations, it
does not require crankshafts with flying arms, split crankpins, or
seven main bearings to be even-firing. This is equivalent to the 90°
V8 in which cylinders fire every 90°. However, in the 120° V6 there
is a primary dynamic imbalance caused by the fact there are an odd
number of cylinders in each bank. At any given time in, each bank, two
cylinders will be moving up while one moves down, and vice-versa. Each
cylinder bank acts like a straight-3 and experiences a strong
vibration at crankshaft speed.

By contrast, in the 90°
V8 engine with a simple flat-plane
crankshaft, each cylinder bank acts like a straight-4 , which is much
smoother than a straight-3. In addition, in 1915 the crossplane
crankshaft was invented, which allowed the secondary vibrations from
one cylinder bank of a V8 to cancel those from the other cylinder
bank. This resulted in an almost perfectly smooth
V8 engine which has
been popular in luxury and sports cars since 1923.

Unfortunately, the crossplane crankshaft does not work for the V6.
There is no way to arrange the 120° V6 so that unbalanced forces from
the two cylinder banks will completely cancel each other. As a result,
the 120° V6 acts like two straight-3s running on the same crankshaft
and suffers from a primary dynamic vibration which requires a balance
shaft to cancel. This has limited its use to trucks and racing cars
where vibration is not as important as in passenger cars.

The 120° layout also produces an engine which is too wide for most
automobile engine compartments, so it is more often used in racing
cars where the car is designed around the engine rather than vice
versa, and light weight and low center of gravity are major
considerations. By comparison, the 180° flat-6 _boxer_ engine is only
moderately wider than the 120° V6, and is an almost fully balanced
configuration with few vibration problems. It can be scaled up to very
large and powerful configurations, so it has been commonly used in
aircraft and in sports/luxury cars where space is not a constraint,
but power and smoothness are important.

Spanish truck manufacturer
Pegaso built the first production 120° V6
for the Z-207 midsize truck in 1955. The engine, a 7.5-litre alloy
Diesel designed under the direction of engineer
Wifredo Ricart uses a
single balance shaft rotating at the speed of the crankshaft

Ferrari introduced a very successful 120° V6 racing engine in 1961.
The
Ferrari Dino 156 engine was shorter and lighter than the 65°
Ferrari V6 engines that preceded it, and the simplicity and low center
of gravity of the engine was an advantage in racing. It won a large
number of
Formula One races between 1961 and 1964 . However, Enzo
Ferrari had a personal dislike of the 120° V6 layout, preferring a
65° angle, and after that time it was replaced by other engines.

Bombardier designed 120° V220/V300T V6 engines for use in light
aircraft. A balance shaft on the bottom of the engine offset the
primary dynamic imbalance. However, it was costly, the market was
small, and it had no overwhelming advantages over the 180° flat-6
engines already in common use in light planes. The design was shelved
in 2006 and there are no plans for production.

Volkswagen 's VR6 engines are a family of V6 engines characterized by
extremely narrow-angle (10.5° or 15°) V configurations. These
engines were developed by the manufacturer in the late 1980s for
transverse engine installations in its front-wheel drive vehicles,
which were originally designed for straight-4 engines. The wider
configuration of a wider angle
V6 engine would have required an
extensive redesign of the vehicles to enlarge the engine compartment.
The narrow angle of 15° (and later 10.5°) between the two cylinder
banks in the
VR6 engine made it much narrower than other V6 designs.
The
VR6 engine is only moderately longer and wider than a straight-4
engine but has 50% greater engine displacement. This made it possible
to install more powerful six-cylinder engines in existing
four-cylinder cars.

The
VR6 engine is also smoother than most V6s without balance shafts.
It uses a firing order of 1,5,3,6,2,4 similar to a straight-6 rather
than a more typical V6 firing order like 1,2,3,4,5,6. In terms of
balance and smoothness the VR6 acts more like a staggered-cylinder
straight-6 rather than a conventional V6.

The narrow angle between cylinders allows the use of just one
cylinder head that covers both cylinder banks, whereas wider angle V
engines require two separate cylinder heads, one for each cylinder
bank. The VR6 arrangement has "twin SOHC" valve gear operating the 24
valves _via_ rocker arms; it is NOT a true
DOHC design. This
simplifies engine construction and reduces costs. Since there is no
room in the V between the cylinder banks for an intake system, all the
intakes are on one side of the engine, and all the exhausts are on the
other side. This system is efficient and simplifies installation into
the engine compartment.

The
Volkswagen VR6 was originally designed as a 2.8 litre engine, but
some versions have been built as large as 3.6 litres in size. In
addition to Volkswagen, VR6 engines have also been used by Audi and
Porsche, although Audi also uses its own designs of wider-angle V6s.
Some other manufacturers have also used VR6 engines in their vehicles.

* The 45° Electro-Motive 6-, 8-, 12-, 16- and 20-cylinder versions
of their 567 Series , 645 Series and 710 Series locomotive, marine and
stationary Diesel engines. This angle is optimum for the more common
8- and 16-cylinder versions. In all of these engines, directly
opposite cylinders always fire 45 degrees apart, so engines other than
8- and 16-cylinder versions are uneven firing. 6-cylinder engines were
only made in the 567 and 645 Series; 20-cylinder engines were only
made in the 645 and 710 Series.
* The 54° GM/Opel V6 , designed to be narrower than normal for use
in small front-wheel drive cars.
* The 65°
Ferrari Dino V6, allowing larger carburetors (for
potentially higher power in race tuning) than a 60° angle and having
crankpins with a 115 degree offset to get the same level of vibration
as in a 60 degree V6, while having an even firing order.
* The 65°
Renault V6 diesel named V9X, has a 65° bank angle for
easier installation of turbocharger inside the vee
* The 72°
Mercedes-BenzBluetec Diesel V6 utilizes a
counter-rotating balance shaft and crankpins offset by 48° to
eliminate vibration problems and make the engine even-firing.
* The 75° Isuzu
V engine used in the
Isuzu Rodeo and Isuzu Trooper
of 3.2 and 3.5 L in both SOHC and
DOHC versions.
Honda also introduced
a 75°
V6 engine in the second generation
Honda NSX .
* The 80°
Honda RA168-E
Formula One engine in the
McLaren MP4/4 .

ODD AND EVEN FIRING

Many older V6 engines were based on
V8 engine designs, in which a
pair of cylinders was cut off the front of V8 without altering the V
angle or using a more sophisticated crankshaft to even out the firing
interval. Most V8 engines share a common crankpin between opposite
cylinders in each bank, and a 90° V8 crankshaft has just four pins
shared by eight cylinders, with two pistons per crankpin, allowing a
cylinder to fire every 90° to achieve smooth operation.

Early 90° V6 engines derived from V8 engines had three shared
crankpins arranged at 120° from each other. Since the cylinder banks
were arranged at 90° to each other, this resulted in a firing pattern
with groups of two cylinders separated by 90° of rotation, and groups
separated by 150° of rotation, causing a notorious _odd-firing_
behavior, with cylinders firing at alternating 90° and 150°
intervals. The uneven firing intervals resulted in rough-running
engines with unpleasant harmonic vibrations at certain engine speeds.

An example is the
Buick 231 odd-fire , which has a firing order
1-6-5-4-3-2. As the crankshaft is rotated through the 720° required
for all cylinders to fire, the following events occur on 30°
boundaries:

ANGLE
0°
90°
180°
270°
360°
450°
540°
630°

ODD FIRING
1
6
5
4
3
2

EVEN FIRING
1
4
5
6
3
2

More modern 90° V6 engines avoid this problem by using split
crankpins , with adjacent crankpins offset by 15° in opposite
directions to achieve an even 120° ignition pattern. Such a 'split'
crankpin is weaker than a straight one, but modern metallurgical
techniques can produce a crankshaft that is adequately strong.

In 1977,
Buick introduced the new "split-pin crankshaft" in the 231 .
Using a crankpin that is 'split' and offset by 30° of rotation
resulted in smooth, even firing every 120°. However, in 1978
Chevrolet introduced a 90° 200/229 V6, which had a compromise
'semi-even firing' design using a crankpin that was offset by only
18°. This resulted in cylinders firing at 108° and 132°, which had
the advantage of reducing vibrations to a more acceptable level and
did not require strengthening the crankshaft. In 1985, Chevrolet's 4.3
(later the Vortec 4300) changed it to a true even-firing V6 with a
30° offset, requiring larger crank journals to make them adequately
strong.

In 1986, the similarly designed 90° PR
V engine adopted the same 30°
crankshaft offset design to even out its firing. In 1988, Buick
introduced a
V6 engine that not only had split crankpins, but had a
counter-rotating balancing shaft between the cylinder banks to
eliminate almost all primary and secondary vibrations, resulting in a
very smooth-running engine.

The
V6 engine was introduced into racing by
Lancia in the early
1950s. After good results with privately entered Aurelia saloons
Lancia set a works competition department in 1951. Four B20 Coupes
were entered in the '51
Mille Miglia and the one driven by Giovanni
Bracco and
Umberto Maglioli caused quite a stir by finishing second
overally after the 4.1-litre
Ferrari driven by Villoresi and Cassani,
a car which had three times more power than the Lancia. After that
encouraging start
Lancia decided to carry on with the endurance racing
program, first with specially prepared Aurelias (called _Da Corsa_)
and then with specially built prototypes. A D24 with a 3,102 cc (189
cu in) V6 making 230 PS (170 kW) won the 1953 Carrera Panamericana
with
Juan Manuel Fangio at the wheel.

After that came the
Ferrari Dino V6. Alfredo
Ferrari (nicknamed
Dino), son of Enzo
Ferrari , suggested to him the development of a 1.5
L
DOHCV6 engine for
Formula Two at the end of 1955. The Dino V6
underwent several evolutions, including an increased engine
displacement to 2,417 cc (147 cu in), for use in the
Ferrari 246
Formula One car in 1958.

The use of a wide 120° bank angle is appealing for racing engine
designers as it permits a low center of gravity . This design is even
considered superior to the flat-6 in that it leaves more space under
the engine for exhaust pipes; thus the crankshaft can be placed lower
in the car. The
Ferrari 156 built for new
Formula One 1.5 L
regulations used a Dino
V6 engine with this configuration.

The Dino
V6 engine saw a new evolution in 1966 when it was adapted to
road use and produced by a Ferrari-
Fiat joint-venture for the Fiat
Dino and Dino 206 GT (this car was made by
Ferrari but sold under the
brand Dino). This new version was redesigned by Aurelio Lampredi
initially as a 65° 2.0 L (120 cu in) V6 with an aluminum block but
was replaced in 1969 by a 2.4 L (150 cu in) cast-iron block version
(the Dino car was renamed the 246GT).

The
Fiat Dino and Dino 246GT were phased out in 1974, but 500 engines
among the last built were delivered to
Lancia , who was like Ferrari
already under the control of
Fiat .
Lancia used them for the Lancia
Stratos which would become one of the most successful rally cars of
the decade. Alfa Romeo V6

The Alfa Romeo V6 was designed in the 1970s by
Giuseppe Busso , the
first car to use them being the
Alfa Romeo 6 . The over-square V6,
with aluminium alloy block and heads, has seen continuous use in road
vehicles, from the Alfetta GTV6 onwards. The 164 introduced a 3.0 L
(180 cu in) V6, a 2.0 V6 turbocharged in 1991 and in 1992, a 3.0 L
DOHC 24-valve version. The Alfa 156 introduced a 2.5 L
DOHC 24-valve
version in 1997. The engine capacity was later increased to 3.2 L (200
cu in), where it found application in the 156 GTA, 147 GTA, 166, GT,
GTV and Spider 916. Production was discontinued in 2005.

Another influential V6 design was the
Renault -
Gordini CH1 V6,
designed by
François Castaing and Jean-Pierre Boudy , and introduced
in 1973 in the Alpine -
Renault A440. The CH1 was a 90° cast-iron
-block V6, similar to the mass-produced PR
V engine in those two
respects but otherwise dissimilar. It has been suggested that
marketing purposes made the Renault-
Gordini V6 adopt those
characteristics of the PRV in the hope of associating the two in the
public's mind.

Despite such considerations, this engine won the European 2 L
prototype championship in 1974 and several European Formula Two
titles. This engine was further developed in a turbocharged 2 L
version that competed in Sports car and finally won the 24 Hours of Le
Mans in 1978 with a Renault-Alpine A 442 chassis.

The capacity of this engine was reduced to 1.5 L to power the Formula
One
Renault RS01. Despite frequent breakdowns that resulted in the
nickname of the 'Little Yellow Teapot', the 1.5 L finally saw good
results in 1979.

Ferrari followed
Renault in the turbo revolution by introducing a
turbocharged derivative of the Dino design (a 1.5 L 120° V6) with the
Ferrari 126. However, the 120° design was not considered optimal for
the wing cars of the era and later engines used V angles of 90° or
less.

Both
Renault and
Ferrari failed in their attempt to win the Drivers'
Championship with V6 Turbo engines. The first turbocharged engine to
win the championship was the
Straight-4BMW .

They were followed by a new generation of
Formula One engines, the
most successful of these being the TAG V6 (designed by
Porsche ) and
the
Honda V6. This new generation of engines were characterized by odd
V angles (around 80°). The choice of these angles was mainly driven
by aerodynamic consideration. Despite their unbalanced designs these
engines were both quickly reliable and competitive; this is generally
viewed as a consequence of the quick progress of CAD techniques in
that era.

In 1989 Shelby tried to bring back the Can-Am series, using the
Chrysler 3.3 L (201 cu in) V6 (not yet offered to the general public)
as the powerplant in a special racing configuration making 255 hp (190
kW). This was the same year that the Viper concept was shown to the
public.

Originally the plan was to produce two versions of this race car, a
255 hp (190 kW) version and a 500 hp (370 kW) model, the 255 hp (190
kW) version being the entry circuit. The cars were designed to be a
cheap way for more people to enter auto racing. Since all the cars
were identical, the winners were to be the people with the best
talent, not the team with the biggest pockets. The engines had Shelby
seals on them and could only be repaired by Shelby's shop, ensuring
that all the engines are mechanically identical.

Only 100 of these 3.3s were ever built. Of these 100, 76 were put
into Shelby Can-Am cars (the only 76 that were ever sold). No
significant amount of spare parts were produced, and the unsold
engines were used for parts/spares. The Shelby specific parts, such as
the upper intake manifold, were never made available to the general
public. According to a small article in the USA Today (in 1989), these
cars were making 250 hp (190 kW) (stock versions introduced in 1990
produced 150 hp or 110 kW) and hitting 160 mph (260 km/h) on the
track. The engine itself was not that far from a standard-production
3.3. The Shelby engine is only making about 50 hp (37 kW) more than
the newest 3.3 factory engines from Chrysler. The Can-Am engine has a
special Shelby Dodge upper intake manifold, a special Shelby Dodge
throttle body, and a special version of the Mopar 3.3 PCM (which had
this engine redlining at 6800 rpm).

Nissan also has a quite successful history of using V6's for racing
in both IMSA and the
JGTC . Development of their V6s for sports cars
began in the early 1980s with the VG engine initially used in the Z31
300ZX . The engine began life as a SOHC, turbocharged 3.0L power plant
with electronic fuel injection, delivering 230 PS (169 kW). The VG30ET
was later revised into the VG30DETT for the
Z32 300ZX in 1989. The
VG30DETT sported both an additional turbocharger and an extra pair of
camshafts, making the engine a genuine
DOHC twin-turbo V6 producing
300 PS (221 kW).
Nissan used both of these engines in its AIMS racing
program throughout the 1980s and 1990s each producing well over 800 hp
(600 kW). In the Japan Grand Touring Car Championship, or
JGTC ,
Nissan opted for a turbocharged version of its VQ30 making upwards of
500 hp (370 kW) to compete in the GT500 class.

The V6 turbo engine was revived for the 2014
Formula One season , and
V6 turbos have been used in the
IndyCar Series since 2012, with
Chevrolet and
Honda currently supplying the engines. Lotus also made
engines in the 2012 season , but pulled out at the end of the year.

MOTORCYCLE USE

Laverda showed a 996 cc V6-engined motorcycle at the 1977 Milan show.
The motorcycle was raced in the 1978 Bol d\'Or .

MARINE USE

Yamaha OX66 engine, as used in their outboard motor range

V6 engines are popular powerplants in medium to large outboard motors
.